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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.cassandra.db.aggregation;
import java.io.IOException;
import java.util.Collections;
import java.util.List;
import org.apache.cassandra.cql3.QueryOptions;
import org.apache.cassandra.cql3.functions.Function;
import org.apache.cassandra.cql3.selection.Selector;
import org.apache.cassandra.db.ClusteringComparator;
import org.apache.cassandra.db.TypeSizes;
import org.apache.cassandra.io.util.DataInputPlus;
import org.apache.cassandra.io.util.DataOutputPlus;
import org.apache.cassandra.schema.ColumnMetadata;
import org.apache.cassandra.schema.TableMetadata;
/**
* Defines how rows should be grouped for creating aggregates.
*/
public abstract class AggregationSpecification
{
public static final Serializer serializer = new Serializer();
/**
* AggregationSpecification that group all the row together.
*/
public static final AggregationSpecification AGGREGATE_EVERYTHING = new AggregationSpecification(Kind.AGGREGATE_EVERYTHING)
{
@Override
public GroupMaker newGroupMaker(GroupingState state)
{
return GroupMaker.GROUP_EVERYTHING;
}
};
/**
* Factory for AggregationSpecification that group all the row together.
*/
public static final AggregationSpecification.Factory AGGREGATE_EVERYTHING_FACTORY = options -> AGGREGATE_EVERYTHING;
/**
* The AggregationSpecification kind.
*/
private final Kind kind;
/**
* The AggregationSpecification kinds.
*/
public enum Kind
{
AGGREGATE_EVERYTHING, AGGREGATE_BY_PK_PREFIX, AGGREGATE_BY_PK_PREFIX_WITH_SELECTOR
}
/**
* Returns the AggregationSpecification kind.
* @return the AggregationSpecification kind
*/
public Kind kind()
{
return kind;
}
private AggregationSpecification(Kind kind)
{
this.kind = kind;
}
/**
* Creates a new GroupMaker instance.
*
* @return a new GroupMaker instance
*/
public final GroupMaker newGroupMaker()
{
return newGroupMaker(GroupingState.EMPTY_STATE);
}
/**
* Creates a new GroupMaker instance.
*
* @param state GroupMaker state
* @return a new GroupMaker instance
*/
public abstract GroupMaker newGroupMaker(GroupingState state);
/**
* Creates a new {@code Factory} instance to create {@code AggregationSpecification} that will build aggregates
* based on primary key columns.
*
* @param comparator the comparator used to compare the clustering prefixes
* @param clusteringPrefixSize the number of clustering columns used to create the aggregates
* @return a new {@code Factory} instance to create {@code AggregationSpecification} that will build aggregates
* based on primary key columns.
*/
public static AggregationSpecification.Factory aggregatePkPrefixFactory(ClusteringComparator comparator,
int clusteringPrefixSize)
{
return options -> new AggregateByPkPrefix(comparator, clusteringPrefixSize);
}
public static AggregationSpecification.Factory aggregatePkPrefixFactoryWithSelector(final ClusteringComparator comparator,
final int clusteringPrefixSize,
final Selector.Factory factory,
final List columns)
{
return new Factory()
{
@Override
public void addFunctionsTo(List functions)
{
factory.addFunctionsTo(functions);
}
@Override
public AggregationSpecification newInstance(QueryOptions options)
{
Selector selector = factory.newInstance(options);
selector.validateForGroupBy();
return new AggregateByPkPrefixWithSelector(comparator,
clusteringPrefixSize,
selector,
columns);
}
};
}
/**
* Factory for {@code AggregationSpecification}.
*
*/
public static interface Factory
{
/**
* Creates a new {@code AggregationSpecification} instance after having binded the parameters.
*
* @param options the query options
* @return a new {@code AggregationSpecification} instance.
*/
public AggregationSpecification newInstance(QueryOptions options);
public default void addFunctionsTo(List functions)
{
}
}
/**
* AggregationSpecification that build aggregates based on primary key columns
*/
private static class AggregateByPkPrefix extends AggregationSpecification
{
/**
* The number of clustering component to compare.
*/
protected final int clusteringPrefixSize;
/**
* The comparator used to compare the clustering prefixes.
*/
protected final ClusteringComparator comparator;
public AggregateByPkPrefix(ClusteringComparator comparator, int clusteringPrefixSize)
{
this(Kind.AGGREGATE_BY_PK_PREFIX, comparator, clusteringPrefixSize);
}
protected AggregateByPkPrefix(Kind kind, ClusteringComparator comparator, int clusteringPrefixSize)
{
super(kind);
this.comparator = comparator;
this.clusteringPrefixSize = clusteringPrefixSize;
}
@Override
public GroupMaker newGroupMaker(GroupingState state)
{
return GroupMaker.newPkPrefixGroupMaker(comparator, clusteringPrefixSize, state);
}
}
/**
* AggregationSpecification that build aggregates based on primary key columns using a selector.
*/
private static final class AggregateByPkPrefixWithSelector extends AggregateByPkPrefix
{
/**
* The selector.
*/
private final Selector selector;
/**
* The columns used by the selector.
*/
private final List columns;
public AggregateByPkPrefixWithSelector(ClusteringComparator comparator,
int clusteringPrefixSize,
Selector selector,
List columns)
{
super(Kind.AGGREGATE_BY_PK_PREFIX_WITH_SELECTOR, comparator, clusteringPrefixSize);
this.selector = selector;
this.columns = columns;
}
@Override
public GroupMaker newGroupMaker(GroupingState state)
{
return GroupMaker.newSelectorGroupMaker(comparator, clusteringPrefixSize, selector, columns, state);
}
}
public static class Serializer
{
public void serialize(AggregationSpecification aggregationSpec, DataOutputPlus out, int version) throws IOException
{
out.writeByte(aggregationSpec.kind().ordinal());
switch (aggregationSpec.kind())
{
case AGGREGATE_EVERYTHING:
break;
case AGGREGATE_BY_PK_PREFIX:
out.writeUnsignedVInt32(((AggregateByPkPrefix) aggregationSpec).clusteringPrefixSize);
break;
case AGGREGATE_BY_PK_PREFIX_WITH_SELECTOR:
AggregateByPkPrefixWithSelector spec = (AggregateByPkPrefixWithSelector) aggregationSpec;
out.writeUnsignedVInt32(spec.clusteringPrefixSize);
Selector.serializer.serialize(spec.selector, out, version);
// Ideally we should serialize the columns but that will break backward compatibility.
// So for the moment we can rebuild the list from the prefix size as we know that there will be
// only one column and that its indice will be: clusteringPrefixSize - 1.
break;
default:
throw new AssertionError("Unknow aggregation kind: " + aggregationSpec.kind());
}
}
public AggregationSpecification deserialize(DataInputPlus in, int version, TableMetadata metadata) throws IOException
{
Kind kind = Kind.values()[in.readUnsignedByte()];
switch (kind)
{
case AGGREGATE_EVERYTHING:
return AggregationSpecification.AGGREGATE_EVERYTHING;
case AGGREGATE_BY_PK_PREFIX:
return new AggregateByPkPrefix(metadata.comparator, in.readUnsignedVInt32());
case AGGREGATE_BY_PK_PREFIX_WITH_SELECTOR:
int clusteringPrefixSize = in.readUnsignedVInt32();
Selector selector = Selector.serializer.deserialize(in, version, metadata);
ColumnMetadata functionArgument = metadata.clusteringColumns().get(clusteringPrefixSize - 1);
return new AggregateByPkPrefixWithSelector(metadata.comparator,
clusteringPrefixSize,
selector,
Collections.singletonList(functionArgument));
default:
throw new AssertionError("Unknow aggregation kind: " + kind);
}
}
public long serializedSize(AggregationSpecification aggregationSpec, int version)
{
long size = TypeSizes.sizeof((byte) aggregationSpec.kind().ordinal());
switch (aggregationSpec.kind())
{
case AGGREGATE_EVERYTHING:
break;
case AGGREGATE_BY_PK_PREFIX:
size += TypeSizes.sizeofUnsignedVInt(((AggregateByPkPrefix) aggregationSpec).clusteringPrefixSize);
break;
case AGGREGATE_BY_PK_PREFIX_WITH_SELECTOR:
AggregateByPkPrefixWithSelector spec = (AggregateByPkPrefixWithSelector) aggregationSpec;
size += TypeSizes.sizeofUnsignedVInt(spec.clusteringPrefixSize);
size += Selector.serializer.serializedSize(spec.selector, version);
break;
default:
throw new AssertionError("Unknow aggregation kind: " + aggregationSpec.kind());
}
return size;
}
}
}
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